I'm a little embarassed to ask this since it is my home turf airport but....

I have never parked in Garage 1 (directly across from the terminal) because I figured you have to take the shuttle bus to the terminal. Instead, I've always parked in Garage 2 which is connected to the main IAD terminal by covered walkway which I always use, thus avoiding a shuttle bus ride.

Is there an underground tunnel from Garage 1 to the terminal or is the shuttle bus the only viable option?